I am surprised how concerned people are getting over mostly driving violations.
Yes, it could be the signs of a certain personality defect, but it just as likely could be the sign of a young 20 something being "young n dumb" making poor choices.
Odd's are he already lives there, that's just how these things go. So I would start by asking myself how long is left on her lease, how much I want to keep her or how happy I am to end this lease term and search for a new tenant.
If it matters to any degree to retain this tenant, if listing for new tenant is a pain, I'd simply call this guy up, I'd be upfront and ask him about all this. I'd be direct, saying I don't put up with any BS, and I see a lot of BS on his record, recent BS, tell me about this, is this just you being you or are you turning a page realizing poor choices lead to poor results and a poor life. And weigh him by his response.
Some people just don't have good mentors in there life, and/or need to learn through mistake. I assume he has some redeeming qualities is this women would have him in her life. I'd at least give him the opportunity to explain himself.
Now keep in mind he at least did 1 correct thing, applied to be added to lease. Many never make that attempt, so there might be redemption there, maybe.